Since HDACs 1, 2, 5 and 6 were differentially expressed and correlate with clinicopathological factors in HCC, we screened the effects of these HDACs on HCC cells proliferation and confirmed that HDAC5 enhances cell proliferation and inhibits apoptosis, indicating that HDAC5 could be the potential target of the chemotherapeutic, AR-42. The gene discussed is HDAC5; the disease is hepatocellular carcinoma.